Are you sure you have the belt threaded right? Looking at your pix the right side pulley is showing the ribs of the belt? That would not be correctIt seems like the new tensioner is the issue. The belt is moving to the back of the idler on the tensioner. I don't see anything else right now that would be wrong.
Thats correct. I cant tell by the pic if thats the belt or the pulley. If its the belt its upside down.The ribbed tensioner pulley is supposed to be to the right of the smooth one.
But the pic is waaaaaay too small to see the alignment, and looking forward rather than straight down. Get a shot straight down, and don't resize it down so much.